Patent GB-811121-A (GB)
Title: Improvements in or relating to the surface-finishing of plasterboard
Inventor: LEITCH DENNIS ARTHUR
IPC: C04B41/48
Filed: 1956-03-02
Abstract: Plasterboard has a resinous surface-finish cured under pressure, said surface-finish comprising a polyepoxide resin or a polyester resin. The cured surface-finish may be on a thin paper sheet firmly adherent to the plasterboard; the paper sheet may itself be stuck to the plasterboard by a cured polyepoxide resin or cured polyester resin. The plasterboard is a building board consisting of set gypsum plaster or comprising a core of set gypsum plaster enclosed between and firmly bonded to two sheets of heavy paper; the board or core of set gypsum plaster may be compact or cellular and may contain a fibrous reinforcing material.  The resinous surface-finish may be produced by applying to the surface a resinous coating comprising a polyepoxide or polyester resin and a curing agent and curing under mechanical pressure or heat and pressure.  The polyepoxide resin may be a polyglycidyl ether of a polyhydric phenol or of a polyhydric alcohol, or may be the resin obtained by treatment of a polyethylenic compound with an oxidizing agent, e.g. those prepared by the oxidation of an unsaturated oil with peracetic acid, or vinyl-cyclo-hexene dioxide which may be prepared by the action of hypochlorous acid on vinyl-cyclo-hexene with subsequent dehydrochlorination of the resulting chlorohydrin.  Further there may be used polyglycidyl esters of polybasic carboxylic acids. The polyepoxides may be used alone or in admixture with mono-epoxide, e.g. phenyl glycidyl ether or styrene oxide.  The polyester resins which may be employed are those fusible resins whose molecules are substantially linear and which may be prepared by the polyesterification of polycarboxylic acid (or anhydride) with a polyhydric alcohol, either the acid or the alcohol or both being unsaturated, preferably modified by a simple ethylenic substance such as styrene or diallyl phthalate.  Also included are the polymers of esters such as diallyl phthalate or bis-(2-allyloxyethyl) carbonate.  The curing of these esters may be effected in the presence of a peroxide, and if desired a peroxide activator, e.g. cobalt naphthenate.  Pressure may be applied during the curing process through a layer of a material to which the resin will not stick, e.g. a sheet of polythene, irradiated polythene, P.T.F.E., or poly-monochlorotrifluoroethylene, or a fabric impregnated with any of these polymers, or aluminium foil or aluminium or aluminium alloy sheet with a coating of bentonite thereon.  The resin may be applied to the surface in solution and dried thereon before curing.  A polyepoxide resin may be applied in the form of a solution of said resin and of a liquid amine in a solvent such as M.E.K., the solvent being then rapidly removed to avoid premature curing of the resin.  The amine may be 3-diethylaminoprophylamine, 3-iso - propylaminopropyl - amine, 3:31 - imino bis - propylamine, piperidine, 1:2 - diaminopropane, dimethylaminopropylamine, or triethylene tetramine.  The plasterboard may be pretreated with a solution of polyepoxide resin or polyester resin and a curing agent, the solvent removed, a thin paper carrying a resinous coating applied, and the whole then cured.  Pigments may be added to the resin to obtain a white or coloured finish.ALSO:A resinous surface-finish may be produced by applying to a surface a resinous coating comprising a polyepoxide or polyester resin and a curing agent and curing under mechanical pressure or heat and pressure.  The polyepoxide resin may be a polyglycidyl ether of a polyhydric phenol or of a polyhydric alcohol, or may be the resin obtained by treatment of a polyethylenic compound with an oxidizing agent, e.g. those prepared by the oxidation of an unsaturated oil with peracetic acid, or vinyl-cyclohexene dioxide which may be prepared by the action of hypochlorous acid on vinyl-cyclohexene with subsequent dehydrochlorination of the resulting chlorohydrin. Further there may be used polyglycidyl esters of polybasic carboxylic acids.  The polyepoxides may be used alone or in admixture with mono-epoxide, e.g. phenyl glycidyl ether or styrene oxide.  The polyester resins which may be employed are those fusible resins whose molecules are substantially linear and which may be prepared by the polyesterification of a polycarboxylic acid (or anhydride) with a polyhydric alcohol, either the acid or the alcohol or both being unsaturated, preferably modified by a simple ethylenic substance such as styrene or diallyl phthalate.  Also included are the polymers of esters such as styrene or diallyl phthalate.  Also included are the polymers of esters such as diallyl phthalate or bis-(2-allyloxyethyl) carbonate.  The curing of these esters may be effected in the presence of a peroxide, and if desired a peroxide activator, e.g. cobalt naphthenate.  The resin may be applied to the surface in solution and dried thereon before curing.  A polyepoxide resin may be applied in the form of a solution of said resin and of a liquid amine in a solvent such as M.E.K., the solvent being then rapidly removed to avoid premature curing of the resin.  The amine may be 3-diethylaminopropylamine, 3-iso-propylamino-propyl - amine, 3 : 21 - imino - bis - propylamine, piperidine, 1 : 2 - diamino - propane, dimethyl-aminopropylamine, or triethylene tetramine and may be used in a proportion of 4-10 per cent based on the weight of the resin. Pigments may be added to the resin to obtain a white or coloured finish.